If you open the file wp-tinymce.php you can see that, in summary, it checks if there’s a zipped version of the tinymce.js in the current folder, case so, it’ll unzip it and return the js minified found inside the zipped file.
The reason this is done is because the js file has 470kb as the zipped file has 206kb.

However, if the program doesn’t find the zipped version, it mixes two js files into one, tinymce.min.js + plugins/compat3x/plugin.min.js.

What we can try to do here is to rename/delete this zipped file, to force the program to use the common .js version instead of the zipped one. To do so:

-If you still have the tinymce folder back up, simply access the new folder and delete the wp-tinymce.js.gz file, otherwise rename this file so the program won’t find it.
-Test this url again and see what it’s going to happen. http://<yoursite>/wp-includes/js/tinymce/wp-tinymce.php

If it still doesn’t word try to replace the entire wp-tinymce.php for this: